Quinone shuttling impels selective electrocatalytic alcohol oxidation: A hydrogen bonding-directed electrosynthesis

Abstract

Electrochemical furfuryl alcohol oxidation to furfural impelled by quinones as electrocatalytic hydrogen shuttle mediators. • The analysis of the effect of 14 quinones in the electrocatalytic oxidation of furfuryl alcohol. • Potential of 3 ring quinones as electro-catalytic hydrogen shuttle mediators. • 3 ring quinones impel the selective oxidation of alcohol to aldehydes. Today development of efficient catalytic systems for selective oxidation of alcohols to aldehydes remains not only a major concern in basic chemistry research but also a significant challenge for the chemical industry. One promising green and sustainable approach to increase the selectivity as well as waste reduction and to minimize the use of toxic and/or hazardous substances is the development of selective electro-catalytic acceptorless dehydrogenation method. By that, it will be possible to facilitate catalyst recovery and reutilization as well as producing only hydrogen as the by-product. Quinones as principal redox-active moieties within natural organic materials play a key role in electron-transport processes of biological systems. Herein, by taking the oxidation of furfuryl alcohol (FA) in dimethyl sulfoxide (DMSO) as a model reaction, 14 quinone derivatives from 3 families (benzoquinones (BQs), naphthoquinones (NQs), and anthraquinones (AQs)) have been surveyed as a hydrogen acceptor mediators. We demonstrate that, only for three-member ring quinones such as 9,10-anthraquinone-2,6-disulfonic acid (AQDS), which are stable during electrocatalysis, a significant increase of the selectivity to furfural with addition of AQDS is achieved. The effect is assigned to strong intermolecular interaction between FA and quinone dianion (Q 2− ) with selective transformation to aldehyde its regeneration to quinone and hydrogen production over cathode surface. This study assesses and validates the potential of quinones as electrocatalytic hydrogen acceptor mediators to impel the selective oxidation of alcohol to aldehydes.